Measurement of the cardiac time intervals of the fetal ECG utilising a computerised algorithm: A retrospective observational study

Abstract

Objective Establish whether the reliable measurement of cardiac time intervals of the fetal ECG can be automated and to address whether this approach could be used to investigate large datasets. Design Retrospective observational study. Setting Teaching hospitals in London UK, Nottingham UK and New York USA. Participants Singleton pregnancies with no known fetal abnormality. Methods Archived fetal ECG's performed using the MonicaAN24 monitor. A single ECG (PQRST) complex was generated from 5000 signal-averaged beats and electrical cardiac time intervals measured in an automated way and manually. Main Outcome measure Validation of a newly developed algorithm to measure the cardiac time intervals of the fetal ECG. Results 188/236 (79.7%) subjects with fECGs of suitable signal:noise ratio were included for analysis comparing manual with automated measurement. PR interval was measured in 173/188 (92%), QRS complex in 170/188 (90%) and QT interval in 123/188 (65.4%). PR interval was 107.6 (12.07) ms [mean(SD)] manual vs 109.11 (14.7) ms algorithm. QRS duration was 54.72(6.35) ms manual vs 58.34(5.73) ms algorithm. QT-interval was 268.93 (21.59) ms manual vs 261.63 (36.16) ms algorithm. QTc was 407.5(32.71) ms manual vs 396.4 (54.78) ms algorithm. The QRS-duration increased with gestational age in both manual and algorithm measurements. Conclusion Accurate measurement of fetal ECG cardiac time intervals can be automated with potential application to interpretation of larger datasets.